Which of the following testing methods is MOST appropriate for assessing whether system integrity has been maintained after changes have been made?

Integration testing focuses on verifying the interfaces and interactions between different modules or components of a system, not primarily on the integrity of existing functionality after a change.

Regression testing specifically aims to ensure that new code, bug fixes, or system changes have not introduced new defects or negatively impacted existing, previously functional parts of the system. By re-running existing test cases, it verifies that the system's integrity and expected behavior are maintained after modifications.

Acceptance testing (UAT) is performed by end-users or clients to verify if the system meets business requirements and is ready for deployment, rather than focusing on the integrity of existing code after technical changes.

Unit testing focuses on testing individual components or units of code in isolation to ensure they function correctly according to their design, not on the overall system integrity after changes have been integrated.